On Tuesday, the bodies of 26 adults and children who apparently died embracing each other were found on a cliff top.
Anticipating questions about the high death toll and the emergency planning, Tsipras stressed the "extreme" scale of the fires.
A firefighter tries to extinguish hotspots during a wildfire in Kineta, near Athens.
"The flames were chasing us all the way to the water", said one victim.
Fire swept through the village 40km (25 miles) north-east of Athens on Monday and was still burning in some areas on Tuesday morning.
People watch a wildfire in the town of Rafina, near Athens, on July 23, 2018.
Above: The red dots on the map represent fires in Greece detected by a satellite July 23, 2018.
Buildings burn in the town of Mati.
Three days of mourning have been declared as officials come to terms with the grim reality that the death toll is likely to rise even further.
The coastguard said four more bodies were retrieved from the sea.
"It's a national tragedy", civil protection agency official Ioanna Tsoupra told public broadcaster ERT.
Fires in 2007 on the southern island of Evia claimed 77 lives. Some 715 people were evacuated by boats to Rafina, the government said.
The first fire started in the Geraneia mountains near Kineta, prompting three villages to be evacuated.
Nine coastal patrol boats, two military vessels and "dozens of private boats" assisted by army helicopters were mobilised to help those stuck in the harbour in Rafina, one of the worst affected areas close to Mati.
Evacuees were transferred to hotels and military camps, while anxious relatives flocked to the area.
Malliri said authorities have received dozens of calls for missing people, adding that some of those reported as missing could be among the dead, or might have already returned to their families without authorities having been informed.
Firefighters are tackling the remaining areas in the two main blazes near the capital, helped by water-dropping aircraft.
Late Monday, an AFP photographer came across a burned out auto and motorcycle with four charred bodies underneath them near the port town of Rafina, one of the worst affected areas about 40 kilometres east of Athens.
"We are dealing with something completely asymmetric", Greece Prime Minister Alexis Tsipras, looking pale, said after cutting short a visit to Bosnia.
A firefighting operation is underway with more than 600 firefighters and 300 engines striving to contain the flames, as the area is surrounded by pines, while Greece has asked the European Union for assistance.
"I saw it with my eyes, it is a real total catastrophe", he said.
Mati is in the Rafina region which is a popular retreat with local holidaymakers, particularly pensioners and children at holiday camps.
The London Daily Mail said authorities suspected there were 15 fires that started at the same time in several locations, "possibly by criminals intending to ransack homes once they were abandoned".
The U.K.'s Foreign Office reported that the fires "have been confined to limited areas, but within those the impact has been high, with significant loss of life". Countries including Cyprus, Spain, Turkey, Italy and Germany, offered support.
There are at least two large fires in Greece.